A Wellington real estate firm has been fined $12,000 after failing to pass on building reports showing the property it sold was a leaky building.

In a recently released decision the Real Estate Agents Authority upheld a complaint against Harcourts' Eastbourne office.

Agents Mary Greig-Clayton and Margaret Lindsay, and their company Team Eastbourne, were found to have not acted in good faith, engaged in conduct likely to bring their profession into disrepute and withheld information.

The complaint centres on a 2011 sale of a house that was later discovered to have up to four leaky windows due to unconsented renovations in 1997.

Rot damage in the bedroom window sills were disclosed in land information filings but the agents had either not read the reports, or read them and had not passed them on to potential buyers.

The REAA complaints assessment committee said the buyer requested the land information reports from the agents, but they were never delivered.

After settlement the new owner found the leaks, which caused "extreme pressure and stress", leading to his pregnant wife being treated in hospital. Leaks also resulted in high power bills and ruined bedding, clothing, carpets and drapes.

The complainant put repair and replacement costs at $27,204. The REAA ordered $7500 of the $12,000 fine to go to the complainant to assist with repairs.